The present invention relates to a spool apparatus for feeding a fiber to a braiding machine or the like and, more particularly, to such apparatus wherein a predetermined tension is maintained on the fiber to prevent it from sagging as the spool apparatus traverses the braider bed or the like.
In general, a braiding process is characterized by the fact of all fiber carriers being in motion to result in intertwined fibers. Multi-ply braiding machines use a matrix array of carriers capable of alternate row and column position shifts. Reversal of the direction of row and column motion during a complete shift cycle produces the intertwining of fibers. Production of complex shapes is possible by adjusting the length of travel (number of spaces shifted) of each row or column.
Multi-ply braiding concepts and machines are disclosed in the patent to Bluck, U.S. Pat. No. 3,426,804, and Florentine, U.S. Pat. No. 4,312,261, the teachings of which are incorporated herein by reference. In the Bluck and Florentine patents, each row and column consists of discrete eyelets or carrier blocks. In other machines presently in use, row motion is accomplished by shifting grooved track members containing fiber carriers. Column motion consists of shifting the discrete fiber carriers. Each of the fiber carriers may be provided with a fiber supply spool from which fiber is fed from the carrier to the braiding apparatus. During movement of the fiber carriers, it is important to maintain a predetermined tension on the fiber being fed to the braiding apparatus for the purpose of taking up slack therein and preventing the fiber from sagging, which can result in interference with other fibers and jamming or malfunctioning of the braiding apparatus.
Although there are presently available spool assemblies for such fiber carriers for taking up slack in the fiber as it is fed to a two-ply braiding apparatus or the like, such assemblies have generally been difficult to manufacture in small sizes suitable for fiber carriers in multi-ply braiding machines or the like. Carriers for supply bobbins and braiding machines are disclosed in the patents to Bull et al, U.S. Pat. No. 4,529,147 and Karg et al, U.S. Pat. No. 3,038,367, the teachings of which are incorporated herein by reference. In the Bull patent, the carrier has a raisable circular cap with a vertical extension which controls the tension of the fiber supply. The Karg patent also has tension adjusting properties, but it along with the Bull patent utilizes carriers that are too long vertically, or require an unacceptable large amount of horizontal space.
The fiber spool apparatus disclosed in the patent to Heine, U.S. Pat. No. 4,700,607, is an improvement over those in the Bull et al and Karg et al patents in that it can be produced in a compact size that is useful for a fiber carrier or the like. In the Heine apparatus, however, a tensioning mechanism is utilized that is separate from the supply bobbin for the fiber.
The braider carriers disclosed in the patents to Moyer, U.S. Pat. Nos. 4,619,180 and 4,736,668 are so constructed that they do not require a separate tensioning mechanism. Instead, the tensioning mechanism is built into the supply bobbin and is in the form of a magnetic clutch and a torsion spring, the spring providing slack control of the fiber to be braided and the clutch providing tensioned feed of the fiber as it is wound off the bobbin. The magnetic clutch of Moyer is somewhat complicated in construction, relatively expensive to manufacture and not completely reliable in operation.
Accordingly, a need has arisen for such a fiber spool apparatus that is simple in construction, compact and reliable in operation. The spool apparatus of the present invention fills this need and operates equally well in any desired orientation.